Process for refining carbonaceous material



H. HOOG PROCESS FOR REFINING CARBONACEOUS MATERIAL Filed Dec. 31, 1948 ur nacc Invcn+or= an Hooq His A zg Scrubber Flq. I

Patented Aug. 26, 1952 PROCESS FOR REFINING' CARBONACEOUSI MATERIAL Han Hoog, Amsterdam, Netherlands, assignor to Shell Development Company, San Francisco, Calif., a corporation of Delaware 1 l l Application December 31, 1948, Serial No. 68,454 a P In the Netherlands J anuary 6, 1948 l 6 Claims.

This invention relates to a new and improved method fordesulfurizing various hydrocarbon oils by catalytic hydrogenation. While all types of sulfur compounds are hydrogenated in the process of the invention, the invention, relates more particularly to a process which destroys thio: phenic compounds and similar so-calledrefractory sulfur compounds. If the oil treated contains nitrogen compounds, oxygen compounds, and/or diolefins or other gum-forming constituents, these are likewise largely, if not substantially completely removed. The Conradson carbon content of the oilis' also materially reduced in such cases where it'is initially high. Q Sulfur-bearing hydrocarbon oils generally contain the sulfur in the form of more than one typeo'f sulfur compound. ,Somefof these compounds, such as alkyl mercaptans and alkyl disulfides, are relatively easily removed by a number of methods, and these are generally called non-refractory sulfur compounds. Other sulfur compoundsjsuch'for example, asthe thiophenic sulfur compounds, are much more diflicult to remove and these are called refractory compounds. The non-refractory sulfur compoundsmay be removed, for example, by treating the oil with or without small amounts of hydrogen with such weakly catalytic materials as certain clays, baux ite, mill scale, pyrites, etc. The refractory sulfur compounds on the other hand require much moregdrastic treatment for their removal. some oil-treating process, such as destructive hydrogenation, hydroforming, and catalytic cracking, effect-a partial removal of such refractory sulfur compounds, but in such processes the oil is materially changed in basic characteristics. by de hydrogenation, cracking and/or other reactions and such desulfurization as is effected is incomplete and more or less incidental. By far the most Jeflicient method for the removal of so'-. called refractory sulfur is through catalyticjhydrogenation, This process although, of very limited application, is well known and is com.- monly'referred to' as hydrodesulfurization.

In hydrodesulfurization the oil to be desulfura ized is treated with a large amount of hydrogen in the presence of an active sulfur resistant hydrogenation catalyst undersuitable conditions of; temperature and pressure. The oil' is usually in-the vapor phase, but. insome caseswhere the amount ,of hydrogen required to completely vaporize-,theoil would; beexorbitant (for example,;, above 20,0Q0cubic :feet per barrel of oil) the oil can be treatedin the liquid phase In the presenceof hydrogen and under the conditions of temperature required the oil is still largely in the vapor phase, but if a liquid phase is present the operation is considered to be a liquid-phase operation. This is due to the fact that the effi ciency ofthe, process is materially changed as soon as'a liquidphase is'present. When a liquidphase is present'the reaction rate is materially lower and also the catalyst suffers a greater rate ofdeo'line "in activity. For these reasons the vapor phase process is'by far the more economical when it can be applied and is preferred. As far 'as can be determined the vapor phase process is the only, one that has been appliedcommercially in the United States to date.

The desulfurization of hydrocarbon oils by hydrodesulfurization has been repeatedly investigated always with the same "results. These investigations have all shown that whenhydrodesulfurizin oils bythdconVentional methods, it is desirablegif not essential, for practical operation to use a large amount of hydrogen. Thus, with amounts of hydrogen in the order I of 2,000-3,000 .cubic feet per barrel of oil, a fairly good desulfurization is obtained for a short time, but the catalyst declines in activity and requires regeneration. As the amount of hydrogen is in creased-to 3,0 00-5,000 cubic feet per barrel of oil the eificiency of the desulfurization isincreased and the life of the catalyst is increased. As the amount of hydrogenis further increased the efficiency of desulfurization falls-off slightly due to decreased time of contact, but the catalyst life is further increased. In the vapor phase process, it is therefore preferred to employ in the order of 5,000-10,000 cubic feet per barrel of oil since with these amounts an excellent desulfiirization may be obtained while operating substantially continuously, i. e. over several hundred hours without, regeneration of the catalyst; The various investigations are consistent in showing that hy, the;use ofsufficient amounts'pff y 3 drogen and operating preferably in the absence of the liquid phase, it is possible to obtain 80% or greater desulfurization or even quite refractory hydrocarbon oils without substantial altera: tion of the basic properties of the oil.

In the past a few improvements in the hydrodesulfurization process have been made through the development of more active and more selective catalysts. The latest and, it is believed, the most efficient known version of this process to date is described in considerable detail in the Transactions of the American Institute of Chemical Engineers, vol. 43, No. 1, page 1, J anuary, 194.7, to which reference is made. In this process excellent desulfurization may be obtained with substantially continuous operation when operating in the absence of a liquid phase.

When operating with a liquid phase present, i. e. when the oil is only approximately 75-90% vaporized, the maximum desulfurization efficiency is obtained when using about 3,500 cubic feet of hydrogen per barrel of oil, but the recommended amount of hydrogen is 4,240cubic feet per barrel of oil, and even with this amount of regeneration of the catalyst after every 2e hours of processing is recommended.

In spite of the fact that a substantially complete desulfurization of hydrocarbon oils may be obtained in a'substantially continuousmanner by the known vapor phase hydrodesulfurization processand less economically in the correspond.- ing liquid phase process, the known hydrodesulfuriz'ationprocess has come into only very limited application. This is due to the fact that the known-process is quite costly. Thus,'even in the isolated instances where by-product hydrogen may be charged at fuel gas value, the vapor phase hydrodesulfur'ization of a typical oil costs in the order of -35 per barrel. This is greater than the price difierential prevailing in the past between lowand high sulfur petroleum oils of equivalent valuein other respects. In spite of the great demand for an efficient desulfurization process, it has, therefore, been uneconomical to apply the known hydrodesulfurization process, even in its most favorable embodiment, except in a few isolated instances where by-product hydrogen has been available and for the treatment of specialty products.

The high costs or the known hydrodesulfurization process is seen, upon analysis, to reside firstly in the large amount of costly high-pressure apparatus required, secondly in the large operating costs (heating, cooling, compressing, etc.).

It has now been found that the desulfurization of hydrocarbon oils by hydrodesulfurization may be carried out equally efiiciently and considerably more economically by operating the process in the particular mannerand under the particular conditions hereinafter described. To aid in the description, reference is had to the attached drawing wherein one form of suitable apparatus for carrying out the invention is illustrated diagrammatically. w

Referring to the drawing, Figure 1, the oil to be desulfurized is introduced into the plant via line I and pump 2. The process is applicable for the desulfurization of sulfur-bearing hydrocarbon oils regardless of their origin or past history. Thus, the feed stock introduced via line I may be of any sulfur-bearing hydrocarbon oil which may be treated under the described conditions while maintaining it substantially in the liquid phase, i. c. with less than 50% vaporiza tion. Thus the process is applicable for the desulfurization of many gasolines and most naphthas. The process is'best adapted, however, to the desulfurization of hydrocarbon oils which are heavier than gasoline and it is particularly advantageous, as compared to the hitherto known process, when desulfurizing heavy oils which are diflicult to vaporize completely. After being' preheated somewhat in the conventional manner by heat exchange in heat exchangers 3 and 4 the oil is further preheated in coil 5 of the fired heating furnace 6. The preheated oil in the liquid phase is then introduced into the catalytic reactor 7 at the top.

Reactor 7 is a vertically disposed cylindrical vessel of suitable dimensions to handle the re-' quired volume of reactants and capable of withstanding the working conditions of temperature and pressure. For reasons which will be pointed out in more detail below it is essential that the reactor have a ratio of length to diameter of at least 5 to ,1 and preferably above 6 to 1. In a typical case reactor 7 is 6 feet in diameter and 54 feet in length and is constructed of 2 inch ,A212 steel with a stainless steel lining.

' The reactor 7 is provided with a suitable perforated plate 8 near the bottom to support the stationary bed of catalyst 9. In order to decrease the weight of catalyst on this support it may be desirable to provide one or more additional supports higherup in the reactor. The reactor 1 is alsoprovided with a suitable means at the-top for distributing the incoming hydrocarbon oil over the upper surface of the bed of catalyst. In

the reactor illustrated a spray cone i0 is pro'-' vided for this purpose. Other suitable means ,may however be used.

The catalyst bed which substantially fills the reactor has a ratio of length to diameter of at least 5 to 1. That part of the liquid oil which flows down through the reactor near the wall is less ei'iiciently contacted. In order to correct this deficiencyth'e reactor is provided with a suitable means for directing the liquid flowing near the walls inwardly toward the center of the bed. In the reactor illustrated short troughs l I are attached to the reactor wall at spaced intervals. A number of open-ended pipes l2 extend fromthe troughs downwardly and inwardly towards the center of the catalyst bed. The arrangement of the troughs II and pipes 12 isshown in moredetail in Figure 2. In operation, the liquid oil descending near the wall of the reactor collects in the troughs ll andthen flows through'pipe I2 to a point near the center of the bed. Any of the known sulfactive hydrogenation catalysts, such as conventionally used heretofore for hyd'rodesulfurization, destructive hydrogenation, hydrofining and related processes may be used in the present process. The preferred catalysts' have as their main active ingredient one or more hydrogenating oxides 0r sulfides of the transition metals, such in particular as molybdenum, nickel and tungsten. These various materials may be used in various combinations with or without such stabilizers and promoters as the oxides and carbonates of K, Ag, Be, Mg, Ca,'Sr, Ba, Ce, Bi, Cr, Th, Si, A1" and Zia 7 These various catalysts may be applied per 'se or in combination with various conventional supporting materials which 7 in certain cases may impart important characteristics to the catalyst. Examples of afew'applicable supporting materials are activated car While any of the mentioned classes orconventional sulfactive hydrogenation catalysts may.

be used, some catalysts are better than-others It is found that a molybdenum oxide catalyst promoted by a minor amount of cobalt oxide and supported upon an activated alumina is a partie ularly good catalyst for this process. ierred catalyst is somewhat similar to that de-. scribed in U. S. Patent No. 2,393,288, butdiflers therefrom in that the oxides of molybdenum and cobalt are incorporated by impregnation in a previously activated alumina and the mole ratio of molybdenum to cobalt is about 5 to 1. The activated alumina used may advantageously be an activated bauxite. Activated Surinam bauxite is particularlysuitable. Thisis the subiq l matter of c'ope'nding application Serial N o, 82,285 filed March 18, 1949.

.Thecatalyst may be in theform of broken fragments such..as. obtained by crushing, or it may f be in. the form of formed pieces suchYas'pellets O'rJcaSt pieces of any suitableform or shape. The catalyst pieces may have an average diameter of a .few millimeters, e. g. 3 mm., up to several centimeters. H V -A H reviously pointed out, thelreaction rate when-aliquidphase is present is lower than when operating iii-the vapor phase. Inthe past when operating witha liquid phase present it has been necessaryto"restrict"the throughput rate to a liquid hourly space velocity (L. H. S .'V.) of about l er-below. (The L; H. S V. isdefinedas the volumes of oil, measuredas' a liquid, which are passed throughthe volume of the catalyst bed in an-hour.) 'ffIn {the processor the invention it is possible to-obtain excellent desulfurization with oil throughput rates in the order of 11* to 5 kg. of oil per liter of catalyst bed per l m n This corresponds to a'liquidhourly space v oc ybetw een about 1.2 and about 6.3. Lowerspae velocities may be required in exceptional cases and higher space velocities may sometimes be permissible.

jIn the process ofthepresent invention the throughput of oil'p'er square'lfoot of horizontal cross section of the catalyst'bed is also important. Qne advantage of the presentpr'ocess isthat high throughput ratesare' not only possible'but are desirable t obtain the maximum desulfurization efficiencyg. ThllSga throughput of .at least 1 gallon-per minute per square foot of cross section is requiredand a throughput of atleast 3 gallons per minute per square foot cross section is pr eferred.. .Typical values are, for instance, .9, and ,9 gallons of oil ;,per minute per square iootof crosssectionn ,Throughputs up to about 2Q gallons perminute'per square foot may be used. ;For a plant of=any givendesired capacity the reactor is constructed to afford throughput rates in this range. -.This requires that the catalyst= =bed hasa high ratio of length todiameter. Asppintedout, this ratio is at least 5:1 and preferablyzat least 6:1. 1 l i A gas rich in hydrogen is introduced simultancously with the oil into the top of the reactor. In practice this gas is recycled gas to which a small amount oi-make-up hydrogen is added. ..Thus, gas from line 13 is mixed'with the} incoming oil and is preheated in the heat exchangers 3 and tand furnace 5. The hydrogen gas passes downthrough the, catalystbed contactwith (The term activated is here used to-in the oil, andthelmixture of gas and liquid oil :are withdrawn together :from the bottom-of the re.-

-actor via line l4. After partial cooling in heat exchangers 3 and 4 the mixture is further cooled incooler I5 and thenpassed to thehigh pres- 1 ,sure separator, l6. The gas. is removed from the 1 1' high pressure separator l6 via line ll and passed i to a conventional hydrogen sulfide scrubber w.

After passing through a trap 19 and beingcom- .pressed inbooster compressor 20, the gas, now

1 substantially free of hydrogen sulfide. is recycled via line l3. Themakeeup hydrogen is introduced via line 2| by, compressor 22. The amount of makeup hydrogen added equals, the amount of hydrogen used up in the hydrogenation reaction plus the amount lost by leakage and by solution the liquid product. The amount of hydrogen used in the.hydrogenationreaction will varyfrom case to case but is typically in the order of 100 200 cubic feet per barrel of oil.

n.. -T at 9 the m 3i vention is the amount of hydrogenlgas recycled.

prior to adding. the make -[11p hydrogen should not exceed ZBOGQlitersper kilogram oil (about 1200 cubic feet per barrel of oil). The preferred range is between liters per kilogram and about .150 liters per kilogram, e. g: 125 litersper kilogram. Excellent results have been; obtained with amounts as ,1ow;as 25 liters per kilogram in some cases.

.The, .hydrod'esulfurization. reaction requires a temperature" of at least 325 .C. and requires that the temperature should not exceed about 4259. C. The reaction is slightly exothermic and there is, therefore, -a small temperature. rise inthe reaction zone. The maximum temperaturein the catalyst bed is controlled within the stated range by controlling the inlet temperature of the preheated feed oil and recycled gas other conventempera ure may also be employed if desired.

The pressure in the process of the inventionds above 450 lbs. per square inch and preferably above 5 O Q p. s..,i. Bressuresin the order, of 0.- 1,000 p. s,i. ;are most practicable. r The high pressure and. the .very. low recycled gas rates employed allow only asmallvaporization of lthoil It .ijs'corisideied that. avoidance of s11 t'antial vaporization important. ii'n tliep'roces'sof the invention the oil in the fre- .action zone is at least 5,6 inthe -liquid phase andfis'; preferably 'inainta'ined above e.' g, in the liquid. phase. The conditions. Qf temperature; pressure and recycled gas rate are preferably adjusted within the indicated limits to allow lessthan 50% of vaporization on the oil. .The liquid. product withdrawn from the hlghr pressure separator .16 is passedthrough a relief valve nintoa lowr-pressure separator 24 where in small amounts of dissolved hydrogensulfide and. hydrogen are released. This gas fiS; With:- drawn viadine 2 5. "The liquid product is withdrawn via line ifiag This liquid product :may be treated in any of-thebonyentional ways tore-.- move remainingtraces of dissolved hydrogen sulfide, e. g. by the ,Girbotol processor by stabilization. j l j When effecting hydrodesulfurization in the manner described, it isnot only possible to obtain an efiicient desulfurization, but'itis possible to effect the desulfurization while operating con tinuously over :hundreds of hours with. no regenerationof the. catalystpr serious decline in the desulfurization efficiency. .3-

as in- 7 J In the following examples. oils having the fol- ;lowin'ginspection data were used. r

V r 8 fidecatalyst (I.. G. Farhen Industrie No. .5615) (mol ratioof W to Ni-.2:1) x 5 mm. pellets).

.r -Re's.,- \c1ume' percent;

150/4C. "Gasoi1s having'esse'nti'ally the properties of feedsNos. 1 and 2 were desulfurized using a 'molybdena-alumina catalyst promoted with cobalt oxide] Thecatalyst was prepared as follows. A commercial activated alumina (Alorco *F-l) in '3 5"m-m. granules was calcined for two hours at 500=(3. and then treated for 16 hours at 100 C. -with a--l5% solutionof hydrochloric acid. After washing and drying the'aluminawas again calcined-#:117 500 Cffor three hoursi The alumina was then impregnated with a'solution' containing ammonium molybdate and cobalt nitrate to give a composite containing 6.5 parts of molybdenum and. 0.8 part of cobalt to each 100 parts of alumina.v The composite was then dried, ground.

to-pass a' 45 meshflsieve and, finally pelletedwith 1%graphite into cylindrical pellets 3 mm. x 5. mm. The pellets were finally heated to 370 C. under nitrogen for-two hours.

The desulfurization was carried out under the following conditions: 1 I

For the first 1 30 hours of operation the L. H.

SJ'V; was 2.4' during which time the oil was 88% desulfurized. The L. H. S. V. was then increased to 3.6 and the process continued without regeneration to 300 hours. The desulfurization remained constant at 80%. The original space velocity was again established and the process was continued. After 407 hours of continuous processing the recycle gas rate was dropped to 125 L/kg. During this period of from 403 to 630 hours the oil was 89% desulfurized. The recycle gas rate was further-reduced toGO -l./kg. This'resulted in a slight loss in efficiency (83% desulfurization), but did not-result in-deactivationof the catalyst since upon returning to the'origin'al condition thede} sulfurization after a total 920 hours was still 86%;

' Following the above experiments the same catalyst was use'dtotreat thesame feed oil using a pressure of atmospheres anda'recycle gas rate of 100 l./kg. Under these conditions (960-1065 processing hours) the oil was only 74% desulfurized. Moreover the. activityof the catalyst declined, since upon returning to '50 atmospheres ,Theprocess was carried out under the following a data of the above pressureand 60 L/kg. of recycle gas only 70 de- 7 sulfurization was obtainedinstead of 83%.

A gas oil havingthe inspection dataof feed No. 3 was desulfurized in the described manner using a commercial-tungsten sulfide-nickel su1-.

conditionsz;

Pressurefatm. e i Q. 50 L; nzs; V. i 1.1

Recycle gas' rate. L/kg. 250

,as described Qab'ovc-a.

Over 230 hours of processing the desulfurizationwas constant at -%1 The L. H. S V. was thenv increased to 3.6; the desulfurization d8? creased to 76% but after a period ofuse it. returneclto 90% when-the original conditions were reestablished showing that the catalyst did not suffer 'any' appreciable decline inactivity. Under the conditions of treatment the oil was approximat.ely85-90%. in the liquid state.

Gas. one having the inspection data of feeds promoted molybdena-alumina catalyst prepared The .desulfurization was carried out under the fol-lowingconditions: I

'IerhberatxireflfQ. 3'15 Pressure, atm '50 H. s v.f 2.4 Recycle gas rate, 1 kg 50 Reactor, ,l./d f 70 Gal; oil/ftP/min. About 1.8

Duriw :the first 235hours of operation the average jdesuliurizati'on'Jamounte'd to 77% after which it leveled o-iiito aiconstant value of 80%. After ,574 hours of operation the recycle gas rate w as;.increased to L/kg. This resulted in a slight; increase in the desulfurization efiiciency t-o:,32%'. After-.1170. hours of operation the gas recycle rat-e was/set at 60 1./k g -and the process was continued. with 83 desulfurization. The catalyst was foundto have 'a-carbon content of The :ahovecata'lyst; after 1259 hours of use, was used, withoutregeneration, for the desulfuflza- .tion of a, flashed "distillate having the inspection feed No.7 under the following At 1260and v1 53.4 proces'sing hours the desul'furi z'ationtwas 79 and-"80% with --no sign of catalyst Nos. 4,5 and 6 were desulfurized with a cobalt 9 deactivation. The Conradson carbon was reduced to 0.01%.

The same catalyst mentioned immediately above, after 2800 hours of use without any regeneration was used to desulfurize a. waxy distillate having the inspection data of the abovementioned feed No. 8 at a gas recycle rate of 50 l./kg. and l./kg. (other conditions unchanged). At these very low rates and with this high sulfur refractory feed the desulfurization was 56% and 53%, respectively. Better desulfurization can be obtained with the feed when somewhat higher gas recycle rates are employed.

In all of the above examples no appreciable cracking took place and the yield of liquid prodnot was in the order of 99%.

Not only is it possible to obtain an efficient substantially continuous desulfurization of various sulfur-bearing hydrocarbon oils, including heavy,

waxy and refractory oils, by operating in the manner indicated, but it is possible to obtain this desired result in a much more economical manner. As pointed out above, by the most efficient and economical hydrodesulfurization process hitherto available the processing costs were in the order of cents per barrel, even when using byproduct hydrogen at fuel gas value, and consequently the hydrodesulfurization of hydrocarbon oils could not be used economically except in a few isolated instances for the treatment of specialty products commanding a high price. The improved economy of the present process allows the hydrodesulfurization to be used economically for a much wider range of materials. The nature and extent of the improved economy may be seen from the following tabulation of the comparative cost of hydrodesulfurizing a typical gas oil by the conventional method and by a typical application of the present method. This comparison is for a typical size plant of 10,000 barrels per day capacity operating under approximately the optimum conditions for 80% desulfurization of a typical gas 011 containing 1.2 sulfur. These processing conditions are as follows:

Vapor phase Present process process Temperature, C 375 375 Pressure, atm 50 50 L. H.S.V 3 1.75 Recycle gas rat 7,000 1. 200 Catalyst... Catelyticliie fimo. fimo. Catalyst cost 47e/lb. 47llb.

Capital Costs (in Thousands of Dollars):

Columns 42 33 Reactor 50 float exchangers 183 131 Separators, etc... 33 29 Pumps and Comp. sso 144 61 Furnaces 115 85' Instrumentation, etc 108 82 Total equipment costs 675 470 Total plant cost, installed 2, 400 2,000

Ope ating Costs (in cents per barrel):

' yst l. 2 2.1 Hydrogen (He/mm. B. t. u.). 0.5 0. 5 Chem icsls O. 3 0. 3 Steam lll l O. 77 0. 43 Electric Pow 0.10 0.07 Fuel Gas... 2.15 1. Cooling Water. 1. 09 0.75 Labor, Maintenance, Interest and Amortization 24. 3 20. 7

Total Manufacturing Costs 30. 5 26. 4

I Molybdena-alumina-coba1t.

10 I claim as my invention:

1. The process for the desulfurization of sulfurbearing hydrocarbon oils which comprises passing the hydrocarbon oil to be desulfurized substantially continuously in the liquid phase downwardly through a bed of stationary granules of a sulfactive hydrogenation catalyst having a ratio of height to elfective diameter of at least 5:1 at a rate between 1 and 20 gallons of oil per minute per square foot of cross section of the catalyst, also. passing downwardly through said bed of catalyst simultaneously with said oil a recycled stream of gas rich in hydrogen in an 7 amount such that the gas withdrawn from said catalyst bed is between 50 and 250 liters per kilogram of said oil, the temperature in said bed of catalyst being maintained between 250 C. and 425 C. and the pressure being maintained above 30 atmospheres, whereby the oil is desulfurized with substantially no destructive hydrogenation and continuing this process for a period in excess of 200 hours without regeneration of the catalyst.

2. The process according to claim 1 further characterized in that the ratio of height tothe eifective diameter of the cataylst bed is at least 6:1.

3. The process according to claim 1 further characterized in that the oil to be desulfurized is passed at a rate of at least 3 gal/min/ft. of catalyst bed and at a liquid hourly space velocity above 1.

4c. The process according to claim 1 further characterized in that the amount of recycle gas withdrawn from the catalyst bed is about l./kg. of oil.

5. The process according to claim 1 further characterized in that the conditions of pressure,

temperature and amount of recycled gas are adjusteol within thegiven limits to prevent more than 20% of the oil from vaporizing in the reaction zone.

6. The process according to claim 1 further characterized in that during the passage of the oil through the catalyst bed oil from the peripheral portions of the catalyst bed is repeatedly directed towards the center.

HAN l-IOOG.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date,

1,944,236 Haslam Jan. 23, 1934 2,029,100 Grosse Jan. 28, 1936 2,392,579 Cole Jan. 8, 1946 2,393,288 Byrns Jan. 22, 1946 2,417,308 Lee Mar. 11, 1947 2,431,920 Cole Dec. 2, 1947 2,437,532 Huifman Mar. 9, 1948 2,441,297 Stirton May 11, 1948 OTHER REFERENCES Elgin et a1., Ind. and Eng. Chem, 22, pp. 1284- 93 (1930). 

1. THE PROCESS FOR THE DESULFURIZATION OF SULFURBEARING HYDROCARBON OILS WHICH COMPRISES PASSING THE HYDROCARBON OIL TO BE DESULFURIZED SUBSTANTIALLY CONTINUOUSLY IN THE LIQUID PHASE DOWNWARDLY THROUGH A BED OF STATIONARY GRANULES OF A SULFACTIVE HYDROGENATION CATALYST HAVING A RATIO OF HEIGHT TO EFFECTIVE DIAMETER OF AT LEAST 5:1 AT A RATE BETWEEN 1 AND 20 GALLONS OF OIL PER MINUTE PER SQUARE FOOT OF CROSS SECTION OF THE CATALYST, ALSO PASSING DOWNWARDLY THROUGH SAID BED OF CATALYST SIMULTANEOUSLY WITH SAID OIL A RECYCLED STREAM OF GAS RICH IN HYDROGEN IN AN AMOUNT SUCH THAT THE GAS WITHDRAWN FROM SAID CATALYST BED IS BETWEEN 50 AND 250 LITERS PER KILOGRAM OF SAID OIL, THE TEMPERATURE IN SAID BED OF CATALYST BEING MAINTAINED BETWEEN 250* C. AND 425* C. AND THE PRESSURE BEING MAINTAINED ABOVE 30 ATMOSPHERES, WHEREBY THE OIL IS DESULFURIZED WITH SUBSTANTIALLY NO DESTRUCTIVE HYDROGENATION AND CONTINUING THIS PROCESS FOR A PERIOD IN EXCESS OF 200 HOURS WITHOUT REGENERATION OF THE CATALYST. 